Display without backlight source has technical advantages such as high contrast, small thickness, large visual angle and fast reaction speed, etc. Thus, Organic Light-Emitting Display (OLED) has become one of the important development directions of the display industries.
The existing organic light-emitting display panel without back lights includes: a cathode, an electron transport layer, a light-emitting layer, a hole transport layer, an anode and a substrate. During operation, a bias voltage is applied between the anode and the cathode of the organic light-emitting display panel, so that holes and electrons can break through the interfacial energy barriers and migrate respectively from the hole transport layer and the electron transport layer to the light-emitting layer, where electrons and holes recombine to generate excitons. The excitons are unstable, and energy can be released. The energy is transferred to the molecules of the organic light-emitting material in the light-emitting layer, so that the molecules transit from a ground state to an excited state. The excited state is very unstable, and thus the excited molecules return to the ground state from the excited state, so that a light emitting phenomenon appears due to radiative transition. In the organic light-emitting display panel, the number of injected carriers, as well as the lightness and efficiency of the organic light-emitting display panel, are determined by the interfacial energy barrier between the organic material and the electrodes. However, in the existing organic light-emitting display panel, due to the relatively high interfacial energy barriers between the electron/hole transport layers and the cathode/anode, the injection capacity of electrons is small, causing poor performance of the organic light-emitting display panel.